JP-A-2011-230353 described below discloses an example of an openable/closable type cover device. The openable/closable type cover device covers an upper part of a printing work space of a screen printer, includes a first cover portion which is attached to a main body of a printer to be swingable around a first swinging shaft line, and a second cover portion which is attached to a free end of the first cover portion to be swingable around a second swinging shaft line which is parallel to the first swinging shaft line, and can open the printing work space upward by being in a two-folded state where the second swinging shaft line moves relatively upward with respect to the first swinging shaft line. The two-foldable type cover device has an advantage that an opening/closing operation while covering a wide work space is easily performed, compared to an integrated swinging type cover device in which an integrated cover swings around one swinging shaft line.